USGS informative article on rocks.

Publishes data about rocks, minerals, gemstones, geology, fossils, dinosaurs, gem trails, rock collecting, jewelry crafts, and more.

Specializes in environmentally significant processes such as crystal growth, metal sorption, trace element partitioning and other surface mediated reactions.

Features funds for information related to mineral resources in Eastern, Central, and Western America.

Searchable picture gallery of minerals in every state in the U.S.

Provides information on the siliceous rock and its various applications.

Source for rock and mineral photography.